With rapid development of mobile communication technology, various mobile terminals such as mobile phones, PDAs (Personal Digital Assistants), notebook computers, etc., have gradually gained popularity. With diversification of functionality, a variety of required power source levels also emerge at the right moment, and management of the power source has become especially important. For example, an excellent mobile terminal will not use a plurality of groups of power source to realize its powerful functionality. One solution is to generate various sub power sources corresponding to various functional applications within the mobile terminals by low dropout linear voltage regulators (referred to as LDOs for short). Therefore, low dropout linear voltage regulators are widely used in various mobile terminal products powered by batteries.
FIG. 1 is a schematic diagram of a low dropout linear voltage regulator in the related art. As shown is FIG. 1, the low dropout linear voltage regulator 100 includes an amplifier 102, a feedback circuit 104, an output transistor 106, and an external voltage-stabilizing capacitor 108. The feedback circuit 104 may include, for example, voltage-dividing resistors RD1 and RD2 connected in series. An output node of the low dropout linear voltage regulator 100 is coupled to a load 110. The output transistor 106 is coupled between an input node receiving an input voltage yin and an output node receiving an output voltage Vout. A gate electrode of the output transistor 106 is coupled to an output node of the amplifier 102. Input ends (including an in phase input terminal and a reversed phase input terminal) of the amplifier 102 are respectively coupled to a reference voltage Vref and a feedback voltage Vf of the feedback circuit.
In the voltage regulator as shown in FIG. 1, although the voltage-stabilizing capacitor 108 may stabilize the output voltage, it increases the volume of the system, and is difficult to achieve system integration and miniaturization/microminiaturization.
In another low dropout linear voltage regulator according to the related art, the external voltage-stabilizing capacitor 108 is omitted.
In system response, all linear voltage regulators will face mutual switching between light loads (low current supply states) and high loads (high current supply states). It is easy to generate a voltage transient in the switching process. If the voltage transient is too large, there will be possibility to cause the whole system to be unstable.
Therefore, it is desired to provide a method of effectively suppressing the voltage transient to reduce impact of the voltage transient and keep the system operating in a controllable condition.
The above information disclosed in this Background section is only for helping the understanding to the background of the present disclosure, therefore, it may include information that does not constitute prior art known by those skilled in the art.